( function () {
/**
 * References:
 *	http://www.valvesoftware.com/publications/2010/siggraph2010_vlachos_waterflow.pdf
 * 	http://graphicsrunner.blogspot.de/2010/08/water-using-flow-maps.html
 *
 */

class Water extends THREE.Mesh {
  constructor(geometry, options = {}) {
    super(geometry);
    this.type = 'Water';
    const scope = this;
    const color = options.color !== undefined ? new THREE.Color(options.color) : new THREE.Color(0xFFFFFF);
    const textureWidth = options.textureWidth || 512;
    const textureHeight = options.textureHeight || 512;
    const clipBias = options.clipBias || 0;
    const flowDirection = options.flowDirection || new THREE.Vector2(1, 0);
    const flowSpeed = options.flowSpeed || 0.03;
    const reflectivity = options.reflectivity || 0.02;
    const scale = options.scale || 1;
    const shader = options.shader || Water.WaterShader;
    const encoding = options.encoding !== undefined ? options.encoding : THREE.LinearEncoding;
    const textureLoader = new THREE.TextureLoader();
    const flowMap = options.flowMap || undefined;
    const normalMap0 = options.normalMap0 || textureLoader.load('textures/water/Water_1_M_Normal.jpg');
    const normalMap1 = options.normalMap1 || textureLoader.load('textures/water/Water_2_M_Normal.jpg');
    const cycle = 0.15; // a cycle of a flow map phase

    const halfCycle = cycle * 0.5;
    const textureMatrix = new THREE.Matrix4();
    const clock = new THREE.Clock(); // internal components

    if (THREE.Reflector === undefined) {
      console.error('THREE.Water: Required component THREE.Reflector not found.');
      return;
    }

    if (THREE.Refractor === undefined) {
      console.error('THREE.Water: Required component THREE.Refractor not found.');
      return;
    }

    const reflector = new THREE.Reflector(geometry, {
      textureWidth: textureWidth,
      textureHeight: textureHeight,
      clipBias: clipBias,
      encoding: encoding
    });
    const refractor = new THREE.Refractor(geometry, {
      textureWidth: textureWidth,
      textureHeight: textureHeight,
      clipBias: clipBias,
      encoding: encoding
    });
    reflector.matrixAutoUpdate = false;
    refractor.matrixAutoUpdate = false; // material

    this.material = new THREE.ShaderMaterial({
      uniforms: THREE.UniformsUtils.merge([THREE.UniformsLib['fog'], shader.uniforms]),
      vertexShader: shader.vertexShader,
      fragmentShader: shader.fragmentShader,
      transparent: true,
      fog: true
    });

    if (flowMap !== undefined) {
      this.material.defines.USE_FLOWMAP = '';
      this.material.uniforms['tFlowMap'] = {
        type: 't',
        value: flowMap
      };
    } else {
      this.material.uniforms['flowDirection'] = {
        type: 'v2',
        value: flowDirection
      };
    } // maps


    normalMap0.wrapS = normalMap0.wrapT = THREE.RepeatWrapping;
    normalMap1.wrapS = normalMap1.wrapT = THREE.RepeatWrapping;
    this.material.uniforms['tReflectionMap'].value = reflector.getRenderTarget().texture;
    this.material.uniforms['tRefractionMap'].value = refractor.getRenderTarget().texture;
    this.material.uniforms['tNormalMap0'].value = normalMap0;
    this.material.uniforms['tNormalMap1'].value = normalMap1; // water

    this.material.uniforms['color'].value = color;
    this.material.uniforms['reflectivity'].value = reflectivity;
    this.material.uniforms['textureMatrix'].value = textureMatrix; // inital values

    this.material.uniforms['config'].value.x = 0; // flowMapOffset0

    this.material.uniforms['config'].value.y = halfCycle; // flowMapOffset1

    this.material.uniforms['config'].value.z = halfCycle; // halfCycle

    this.material.uniforms['config'].value.w = scale; // scale
    // functions

    function updateTextureMatrix(camera) {
      textureMatrix.set(0.5, 0.0, 0.0, 0.5, 0.0, 0.5, 0.0, 0.5, 0.0, 0.0, 0.5, 0.5, 0.0, 0.0, 0.0, 1.0);
      textureMatrix.multiply(camera.projectionMatrix);
      textureMatrix.multiply(camera.matrixWorldInverse);
      textureMatrix.multiply(scope.matrixWorld);
    }

    function updateFlow() {
      const delta = clock.getDelta();
      const config = scope.material.uniforms['config'];
      config.value.x += flowSpeed * delta; // flowMapOffset0

      config.value.y = config.value.x + halfCycle; // flowMapOffset1
      // Important: The distance between offsets should be always the value of "halfCycle".
      // Moreover, both offsets should be in the range of [ 0, cycle ].
      // This approach ensures a smooth water flow and avoids "reset" effects.

      if (config.value.x >= cycle) {
        config.value.x = 0;
        config.value.y = halfCycle;
      } else if (config.value.y >= cycle) {
        config.value.y = config.value.y - cycle;
      }
    } //


    this.onBeforeRender = function (renderer, scene, camera) {
      updateTextureMatrix(camera);
      updateFlow();
      scope.visible = false;
      reflector.matrixWorld.copy(scope.matrixWorld);
      refractor.matrixWorld.copy(scope.matrixWorld);
      reflector.onBeforeRender(renderer, scene, camera);
      refractor.onBeforeRender(renderer, scene, camera);
      scope.visible = true;
    };
  }

}

Water.prototype.isWater = true;
Water.WaterShader = {
  uniforms: {
    'color': {
      type: 'c',
      value: null
    },
    'reflectivity': {
      type: 'f',
      value: 0
    },
    'tReflectionMap': {
      type: 't',
      value: null
    },
    'tRefractionMap': {
      type: 't',
      value: null
    },
    'tNormalMap0': {
      type: 't',
      value: null
    },
    'tNormalMap1': {
      type: 't',
      value: null
    },
    'textureMatrix': {
      type: 'm4',
      value: null
    },
    'config': {
      type: 'v4',
      value: new THREE.Vector4()
    }
  },
  vertexShader:
  /* glsl */
  `

		#include <common>
		#include <fog_pars_vertex>
		#include <logdepthbuf_pars_vertex>

		uniform mat4 textureMatrix;

		varying vec4 vCoord;
		varying vec2 vUv;
		varying vec3 vToEye;

		void main() {

			vUv = uv;
			vCoord = textureMatrix * vec4( position, 1.0 );

			vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
			vToEye = cameraPosition - worldPosition.xyz;

			vec4 mvPosition =  viewMatrix * worldPosition; // used in fog_vertex
			gl_Position = projectionMatrix * mvPosition;

			#include <logdepthbuf_vertex>
			#include <fog_vertex>

		}`,
  fragmentShader:
  /* glsl */
  `

		#include <common>
		#include <fog_pars_fragment>
		#include <logdepthbuf_pars_fragment>

		uniform sampler2D tReflectionMap;
		uniform sampler2D tRefractionMap;
		uniform sampler2D tNormalMap0;
		uniform sampler2D tNormalMap1;

		#ifdef USE_FLOWMAP
			uniform sampler2D tFlowMap;
		#else
			uniform vec2 flowDirection;
		#endif

		uniform vec3 color;
		uniform float reflectivity;
		uniform vec4 config;

		varying vec4 vCoord;
		varying vec2 vUv;
		varying vec3 vToEye;

		void main() {

			#include <logdepthbuf_fragment>

			float flowMapOffset0 = config.x;
			float flowMapOffset1 = config.y;
			float halfCycle = config.z;
			float scale = config.w;

			vec3 toEye = normalize( vToEye );

			// determine flow direction
			vec2 flow;
			#ifdef USE_FLOWMAP
				flow = texture2D( tFlowMap, vUv ).rg * 2.0 - 1.0;
			#else
				flow = flowDirection;
			#endif
			flow.x *= - 1.0;

			// sample normal maps (distort uvs with flowdata)
			vec4 normalColor0 = texture2D( tNormalMap0, ( vUv * scale ) + flow * flowMapOffset0 );
			vec4 normalColor1 = texture2D( tNormalMap1, ( vUv * scale ) + flow * flowMapOffset1 );

			// linear interpolate to get the final normal color
			float flowLerp = abs( halfCycle - flowMapOffset0 ) / halfCycle;
			vec4 normalColor = mix( normalColor0, normalColor1, flowLerp );

			// calculate normal vector
			vec3 normal = normalize( vec3( normalColor.r * 2.0 - 1.0, normalColor.b,  normalColor.g * 2.0 - 1.0 ) );

			// calculate the fresnel term to blend reflection and refraction maps
			float theta = max( dot( toEye, normal ), 0.0 );
			float reflectance = reflectivity + ( 1.0 - reflectivity ) * pow( ( 1.0 - theta ), 5.0 );

			// calculate final uv coords
			vec3 coord = vCoord.xyz / vCoord.w;
			vec2 uv = coord.xy + coord.z * normal.xz * 0.05;

			vec4 reflectColor = texture2D( tReflectionMap, vec2( 1.0 - uv.x, uv.y ) );
			vec4 refractColor = texture2D( tRefractionMap, uv );

			// multiply water color with the mix of both textures
			gl_FragColor = vec4( color, 1.0 ) * mix( refractColor, reflectColor, reflectance );

			#include <tonemapping_fragment>
			#include <encodings_fragment>
			#include <fog_fragment>

		}`
};

THREE.Water = Water;
} )();
